Very informative video about the advances in the integration of Adobe's Kuhler to Adobe Illustrator. If you have no idea what Kuhler is, you need to check this out. Especially if you struggle in any way with making color combinations.

Great tutorial on using Clipping Masks in Illustrator. A little bit about the Pathfinder Palette too!

This tutorial was created using Adobe Illustrator CS3, but even if you don't have CS3, there is some good information about the concepts and application of Clipping Masks. Also includes tips on integrating your artwork with Photoshop and Flash.